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After clearcutting xerothermic oakwoods once natural in the forest-steppe loess regions of Hungary, the perennial understorey grass Brachypodium pinnatum has been persisting for decades by establishing microhabitats from shade to full sun. In this paper, we explore variation in leaf anatomy for plants growing in different microhabitat light regimes (full shade under oak canopy, half shade near shrubs, and in unshaded grassland) in situ, and for plants reciprocally transplanted between these microhabitats. Leaf lamina thickness and mesophyll thickness were about 1.5 times greater in the grassland in situ than in oak subcanopy due to an additional layer of mesophyll cells and to 25-32% taller mesophyll cells. Mesophyll thickness and the proportion of veins plus sclerenchyma were lower for plants transplanted from either full or half shade to full sun than in situ plants in the grassland. Parenchymatous bundle sheath tended to be thicker in the grassland than in the two other microhabitats. Mean intervenial distance remained invariable among microsites. These adjustments in leaf anatomy may be a considerable part, but presumably not the dominant component of the medium-term (one year) light acclimation of B. pinnatum and the species success in microsites with contrasting light climate appearing side-by-side during secondary vegetation succession.
Leaf morphology, coarse structure and anatomy were compared for two invasive C 4 , two non-invasive C 4 , and two expanding native C 3 grass species grown in their original, high-light semiarid temperate habitat, and in a growth room under variable moderate light and favourable supply of water and nutrients. It was hypothesised that (H 1 ) among C 4 grasses leaf structural response will be greater for invasive than for non-invasive species, and (H 2 ) for plants of high spreading capacity C 4 species will be less responsive than C 3 species. Leaf mass per area was lower in the growth room than in the field by 43.4–54% and 5.7–21.2% for grasses of high spreading capacity and for non-invasive C 4 species, respectively. Little or no response was observed in the proportion of epidermis and mesophyll, but the proportional area of veins plus sclerenchyma was greater in the field than in the growth room for the invasive C 4 Sorghum halepense , and the spreading C 3 Bromus inermis and Calamagrostis epigeios , while it did not differ for the two non-invasive C 4 grasses and the invasive C 4 Cynodon dactylon . Leaf intervential distance was invariant for C 4 grasses (except for the non-invasive Chrysopogon gryllus ) and the C 3 C. epigeios , but changed by 25.1% for the C 3 B. inermis . These results suggest that among C 4 grasses invasive species expceed non-invasive ones in the plasticity of leaf coarse structure, but not that of leaf morphology and anatomy. However, leaf structure was not less plastic in invasive C 4 than in expanding C 3 grasses except for intervential distance.
Abstract
Introduction
Left ventricular (LV) twist is considered an essential part of LV function due to oppositely directed LV basal and apical rotations. Several factors could play a role in determining LV rotational mechanics in normal circumstances. This study aimed to investigate the relationship between LV rotational mechanics and mitral annular (MA) size and function in healthy subjects.
Methods
The study comprised 118 healthy adult volunteers (mean age: 31.5 ± 11.8 years, 50 males). All subjects had undergone complete two-dimensional (2D) Doppler echocardiography and three-dimensional speckle-tracking echocardiography (3DSTE) at the same time by the same echocardiography equipment.
Results
The normal mean LV apical and basal rotations proved to be 9.57 ± 3.33 and −3.75 ± 1.98°, respectively. LV apical rotation correlated with end-systolic MA diameter, area, perimeter, fractional area change, and fractional shortening, but did not correlate with any end-diastolic mitral annular morphologic parameters. The logistic regression model identified MA fractional area change as an independent predictor of ≤6° left ventricular apical rotation (P < 0.003).
Conclusions
Correlations could be detected between apical LV rotation and end-systolic MA size and function, suggesting relationships between MA dimensions and function and LV rotational mechanics.
Left atrial (LA) distension has been demonstrated to be linked with aortic stiffness in different patient populations. Three-dimensional (3D) speckle-tracking echocardiography (STE) seems to be a promising tool for volumetric and functional evaluation of the LA. The aim of the present study was to determine whether correlations exist between 3DSTE-derived LA volume-based and strain parameters characterizing all phasic functions of the LA and echocardiographic aortic elastic properties in healthy subjects. The study included 19 healthy volunteers (mean age: 37.9 ± 11.4 years, 11 men) who had undergone complete two-dimensional (2D) Doppler transthoracic echocardiography extended with the assessment of aortic elastic properties and 3DSTE. Results: None of LA volumes correlated with echocardiographic aortic elastic properties. Active atrial stroke volume correlated with aortic stiffness index (ASI, r = 0.45, p = 0.05). None of other volume-based functional properties signifcantly correlated with aortic stiffness parameters. Global peak 3D strain correlated with aortic strain (r = ‒0.46, p = 0.05). global radial pre-atrial contraction strain correlated with ASI (r = ‒0.49, p = 0.04) and AS (r = ‒0.50, p = 0.04). Conclusions: Correlations exist between 3DSTE-derived LA functional parameters and eschocardiographic aortic elastic properties in healthy subjects.
Introduction
Myocardial contractility of the left ventricle (LV) is related to arterial distensibility. Sport activity is frequently associated with changes in both LV and arterial functions. This study aimed to find correlations between three-dimensional speckle-tracking echocardiography-derived segmental LV deformation parameters and echocardiographically assessed aortic stiffness index (ASI) in athletes. This study comprised 26 young elite athletes (mean age: 26.7 ± 8.4 years, nine men).
Results
Among segmental circumferential strains (CSs), only that of apical anterior (r = 0.40, p = 0.05), septal (r = 0.47, p = 0.01), inferior (r = 0.59, p = 0.001), lateral (r = 0.44, p < 0.05), and midventricular anteroseptal (r = 0.44, p < 0.05) segments correlated with ASI, whereas LV-CS of the midventricular anterior segment showed a correlation tendency. Only longitudinal strain of basal anteroseptal (r = −0.46, p < 0.05) and inferoseptal (r = −0.57, p < 0.01) segments showed correlations with ASI, whereas that of the basal anterior segment had only a tendency to correlate. Some segmental multidirectional strains also correlated with ASI.
Conclusions
Correlations could be demonstrated between increased aortic stiffness and circular function of the apical and midventricular LV fibers and longitudinal motion of the basal septum and LV anterior wall (part of LV outflow tract) in maintaining circulation in the elite athletes.
Tissue level myocardial perfusion is one of the most important prognostic factors after successful recanalisation of the occluded coronary artery in patients suffering acute ST elevation myocardial infarction (STEMI). The primary objective of the present study was to examine the relationship between videodensitometric myocardial perfusion parameters as assessed on coronary angiograms directly following successful recanalization therapy and magnetic resonance imaging (MRI)-derived myocardial tissue loss late after STEMI. The study comprised 29 STEMI patients. Videodensitometric parameter Gmax/Tmax was calculated to characterize myocardial perfusion, derived from the plateau of grey-level intensity (Gmax), divided by the time-to-peak intensity (Tmax). Myocardial loss index (MLI) was assessed by cardiac MRI following 376 ± 254 days after PCI. Results: Signifcant correlations could be demonstrated between MLI and Gmax (r = 0.36, p = 0.05) and Gmax/Tmax (r = 0.40, p = 0.03) using vessel masking. Using receiver operating characteristic curve analysis, Gmax/Tmax < 2.17 predicted best MLI = 0.3, 0.4, 0.5 and 0.6 with good sensitivity and specifcity data, while Gmax/Tmax < 3.25 proved to have a prognostic role in the prediction of MLI = 0.7. Conclusions: Selective myocardial tissue level perfusion quantitative measurement method is feasible and can serve as a good predictor of myocardial tissue loss following STEMI and revascularization therapy.
